S02 - Session O3 - Exploiting the Swiss Apple Core Collection for breeding tomorrow's apple cultivars

Authors: Giovanni Broggini *, Kellerhals Markus, Bruno Studer

Plant genetic resources represent a valuable reservoir of genetic diversity that breeding programs can exploit. However, the number of inventoried crop varieties is usually large, and preservation and detailed description of all of them is laborious and expensive. Core collections represent a compact form to preserve the genetic diversity of crop species. In addition to mere preservation, a detailed description of the phenotypic diversity within core collections allows identifying variety-specific traits to be used efficiently in breeding programs. Replication of core collections at different locations can unravel genotype-by-environment interactions, which are relevant to understanding how climatic differences affect relevant traits. Especially in apple breeding, where genetic diversity in the few commercially successful varieties is low, broadening the genetic base is a crucial element to adapt cultivars to new challenges such as environmental changes or the occurrence of new pests and diseases as well as abiotic stress. To describe Swiss apple genetic resources and support apple breeding, the Swiss Federal Office for Agriculture initiated the establishment of a Swiss Apple Core Collection. It consists of 330 old Swiss apple varieties and accessions and 27 reference genotypes. Three trees per genotype were planted at three climatically different locations each. The description of a broad range of cultivar traits, with the help of the latest phenotyping technologies, made it possible to identify variations for traits that will become important in the future. Priority was given to a detailed description of fruit quality features and tree performance. In the second phase, attention was given to diseases and biotic stress tolerance. Combining phenotypic information with genome-wide sequence data will allow identifying loci of interest and developing molecular markers associated with these. Including these traits in apple breeding programs will further enhance the development of diverse, resilient apple cultivars.